1. Field of the Invention
The invention relates to an electric power supply system, and more particularly, an electric power supply system and an electric power supply method that supplies electric power from a secondary battery provided in a vehicle to a building.
2. Description of the Related Art
In recent years, with the aim of reducing CO2 in an attempt to prevent global warming, hybrid vehicles that are provided with a secondary battery and use both an engine and a motor as a power source, have become increasingly popular, and electric vehicles that are provided with a secondary battery are also starting to receive attention.
Moreover, technology for supplying electric power from a secondary battery provided in such a vehicle to a house has been proposed (Japanese Patent Application Publication No. 2008-100645 (JP-A-2008-100645), for example).
More specifically, JP-A-2008-100645 proposes technology to obtain an allocated amount of electric power required for normal use from the amount of electric power that is consumed daily by an electric vehicle, and supply electric power from the battery to a house in an amount that does not exceed the difference between the amount of electric power remaining in the battery and the allocated amount of electric power.
However, the amount of electric power that is able to be supplied from the vehicle to the house is different with an electric vehicle than it is with a hybrid vehicle. That is, a hybrid vehicle is able to run using gasoline, so all of the electric power can be supplied to the house. However, with the technology described in JP-A-2008-100645, no consideration is given to the type of battery, such as the battery of an electric vehicle or the battery of a hybrid vehicle, so there remains room for improvement in terms of supplying an appropriate amount of electric power to a house.
Also, with the technology described in JP-A-2008-100645, no consideration is given to the type of electric power that is charged to the vehicle, such as electric power that has been charged during hours when the electricity rates are low, such as nighttime power, and electric power that has been charged during normal hours, so there remains room for improvement in this area as well.